Only in rare cases will Array.Sort perform in O(n) time. More likely, it will be O(n log n) time.
See here for more details: https://docs.microsoft.com/en-us/dotnet/api/system.array.sort?view=netframework-4.8

but you are not meeting the requirements

Done in O(n) time with comments! Very well done!

myjinxin2015 is a javascript wizard I would do well to learn from

Hacker solution for sure! Makes no sense to this javascript noob & works and described. Well done!
I'll be running this through a debugger to figure it out!

@Voile
IDK about JS terminology, but in C/C++ "expression" is something that has a value, so

• the first part in for (...) isn't an expression;
• var a=1,b=2,c=3 is a statement but not an expression; the only expressions here are 1, 2 and 3;
• etc.

The opening part of a for loop in JS consists of 3 expressions (separated by ;), and each statement can have multiple run-off statements in a row (separated by , instead). Since var a=1,b=2,c=3 and such is a valid (multi-statement) expression it's a valid for loop. In fact it's valid in C and other languages too: int a,b,c; for(a=1,b=2,c=3;a<10;a++); is valid and works just as intended.

Of course, putting too much stuff inside the for loop is not my style ;-) But I don't think it's that unreadable in the first place.

Im a newbie to javascript and this website. Not a total newb, though will not spout credentials. Im trying to understand the code and the culture here. I'm not trying to start a flame war, trying to engage with others

Tried to be respectful in my questions and I have not.

I am sorry that I have been passive aggressive with "You see beautiful, I see can't read". Did not realize that such discussions are passive-aggressive. Will not speak of such in the future. What I wanted was an explaination on a novel(to me) for loop with multiple variable initializations in the intial expression. I should not have stated my opinion on whether the code was golfed or not.

Thank you for the clarification,(especially Avanta) all who have contributed to this discussion.

As I understand now:

i is the control var in the initial expression of the for loop. The initialExpression of the for loop can contan multiple variables in the scope of the loop.

If you keep mentioning "is this a newb thing" twice in one comment perhaps you should just admit that you're a newbie and you're probably not qualified to give strong opinions about this.

(Yes, I'm talking about those "this is clever but not best practice" comments, they've since long become passive-aggressive assertions about "code that is short and does the task but I don't like it so I have to diss it".)

Also, this is JS, not C or Java or anything. Their syntax look similar but they're very different.

This code reminds me of the book "If Hemingway Wrote JavaScript". Beautiful solution

Of course one can initialize more than one variable per line. That is not my confusion.
Is i is the loop control var?
Are l and r part of the loop control logic?
That is what is unclear about the code
Am i correct in assuming that the code would work just the same if
l and r were initialized out side the loop?
Thank you for taking time to explain

you can initialise more than one variable on a line, eg:
var a, b, c = 1, d = 5;